Traffic lights are a suggestion by tvor
Cabs in Rome, well all cars really, are small. There are taxi ranks which are the best place to catch a cab as there are rogue drivers out there. You can ask how much it will cost to get to a certain place before you get in. Four of us took a taxi to St. Peter's Square one morning and the journey was like a Disney thriller ride! The cab driver swooped in and out of traffic, just like all the other drivers, and then got in to a hollering match with a well dressed man on a scooter. We did pick up a few handy Italian insults to keep in mind for future use LOL! In the end the scooter driver spit over his shoulder at the cab driver with a few hand gestures but the wind caught him and it landed all over his nice leather jacket. We all were in puddles of laughter over that.
It was, i think, a typical cab journey but other journeys we took were less eventful. A cab ride from the hotel in an outlying area of rome to the center was at the time 24,000 Lira which was about $24 Canadian at the time. It's now all euros so i can't say what the prices would be like now.